New Mexico Geological Society Annual Spring Meeting — Abstracts

The southern Sangre de Cristo Mountains of northern New Mexico contain evidence of Quaternary glaciation, including a distinctive set of late Holocene moraines in the Lake Katherine cirque of the Winsor Creek drainage basin. Previous work by Wesling (1988) revealed a Neoglacial-age moraine in this cirque based on a basal radiocarbon date of 3600 y.b.p. Moraines range in age down-basin in the Stewart Lake area from Bull Lake and Pinedale to Latest Pleistocene and a possible Triple Lakes equivalent Neoglacial moraine in the Lake Katherine cirque.

Alpine catchments such as lakes and bogs are becoming an increasingly popular source for obtaining high-resolution proxy data of past climate change. In this study, a number of sedimentary records were recovered from alpine lakes and bogs trapped behind Pinedale-age moraines within the Stewart Lake area using a Livingston soft-sediment piston corer. These cores are typically composed of an upper peat-rich interval underlain by a thin layer of coarse detrital sand containing a basal charcoal horizon, followed by a thick sequence of lake clays that become finely laminated at the base of the record. In the deepest series of cores, a thin basal interval of rock flour-rich clay is present, suggesting deposition coincident with proximal glacial ablation.

Radiocarbon analysis of charcoal, plant macrofossils, and bulk sediments within recovered cores provide age control on the rates of deposition in these systems. In addition, total organic carbon, magnetic susceptibility, and sedimentologic analysis are being conducted on the recovered cores. Preliminary results show excellent correlation between these different proxies and the ultimate timing of significant climatic perturbations in this region over the last 5,000 years, and possibly the last 14,000 years. The most significant depositional change in the core (peat/ clay transition) is coincident with the formation of the dated Neoglacial moraine and a notable mid-Holocene wetting period in the Estancia Basin of central New Mexico.